A strange div bug on Linux x86_64, (both dmd & ldc2): long -5000 / size_t 2 = 9223372036854773308
Patrick.Schluter at bbox.fr
Thu Aug 13 21:06:58 UTC 2020
On Thursday, 13 August 2020 at 19:03:38 UTC, H. S. Teoh wrote:
> On Thu, Aug 13, 2020 at 06:51:09PM +0000, mw via Digitalmars-d
>> On Thursday, 13 August 2020 at 18:40:40 UTC, matheus wrote:
>> > On Thursday, 13 August 2020 at 13:33:19 UTC, bachmeier wrote:
>> > > ...
>> > > The source of wrong behavior is vec.length having type
>> > > ulong. It
>> > > would be very unusual for someone to even think about that.
>> > May I ask what type should it be?
>> Signed (size_t, the length of the machine's address space)
> size_t is unsigned, because the address space of a 64-bit
> machine is 2^64, but a signed value would only be able to
> address half of that space (2^63).
While the rationale makes sense and I'm definitely in the camp of
unsigned size_t, signed addresses can without problem access the
whole address range. The other half will then be addressed with
negative numbers. The last address 0xFFFFFFFFFFFFFFFF is -1L
(that's what was used on Apple II integer basic, which only had
signed 16 bit integers as variable type, that's why entering
monitor was done with CALL -151 and not CALL 65385).
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